1. Field of the Invention
This invention relates to a bolt-tightened type coupling which is used to connect pipes, hoses, tubes or the like and, for example, can be used to connect an outlet hose of a turbo-charger to an engine inlet passage. More particularly, this invention relates to a bolt-tightened type coupling comprising a pair of semi-circular coupling halves having one end of each half pivotably connected to one another and the other end of each half mutually connected by means of a bolt and nut, in which the bolt is prevented from being removed, but is stably held by one of the coupling halves to improve productivity and to attain an easy assembly operation.
2. Description of the Related Art
In the prior art, a bolt-tightened type coupling, such as shown in FIG. 1, has been conventionally known and used to connect pipes, hoses, or any separated members.
The known coupling 1 comprises a pair of semi-circular arc-shaped coupling halves 2a and 2b having one end of each half provided with flanges 3a and 3b, respectively, which are pivotably connected to one another by a connecting ring 4, so that these coupling halves 2a and 2b can cooperate to open or close to encircle, for example, a pipe, not illustrated in the drawings. The other ends of the coupling halves 2a and 2b are provided with flanges 5a and 5b, respectively, which have respective bolt inserting holes 6a and 6b, so that a bolt 7 can be inserted through the bolt inserting holes 6a and 6b and engaged with and screwed into a corresponding nut 8.
However, in the conventionally known bolt-tightened type coupling 1 as mentioned above, when the coupling 1 is to be installed, a bolt 7 must be first inserted into the bolt inserting hole 6 of one 2 of the coupling halves 2a and 2b, then the bolt inserting hole 6 of the other coupling half 2 must be placed over the tip of the bolt 7, while the head of the bolt 7 is pushed by the operator's hand, and the nut 8 must then be put on the tip of the bolt 7 to be engaged with and screwed thereto.
Recently, however, an electric nut-screwing machine, sometimes called an "impact wrench" or a "nut driver" is frequently used particularly in a mass-production factory to improve the productivity and increase the speed of the assembly operation. When such an electric machine is used to install a coupling 1, it is very difficult or almost impossible to hold the bolt 7 by hand in a continuous mass-production line, in view of its assembling speed, automatic operation or productivity. Therefore, it is required that the bolt 7 is held by the coupling 1 beforehand.
In view of the above, it has been previously proposed that such a bolt is, beforehand, fixed to one of the coupling halves by a welding or the like. In this case, however, it is very difficult to insert the tip of the bolt into the bolt inserting hole of the other coupling half, since the bolt is immovably fixed to the one of the coupling holes. Therefore, the assembling operation would be very difficult.
It has also been proposed that, using a welding or the like, such a bolt is, beforehand, provisionally mounted on one of the coupling halves. In this case, however, another member is additionally required and it must be mounted on. That is to say, the bolt must be provisionally inserted into the bolt inserting hole and the washer is mounted on the tip of the bolt to provisionally mount the bolt on one of the coupling halves. Therefore, the assembly operation would also be substantially difficult and a reduction in the production cost would be difficult.